The phenomenon that occurs when two individuals are in online chat and type the same exact, or nearly exact, thing simultaneously. Named after Star Trek's Mr. Spock, who had the ability to read minds.

John: I can't wait to see you in San Francisco in three weeks.
Karen: I can't wait until San Francisco in a few weeks.
John: See? We did it again. It's like we read each others' minds. It's a Vulcan Mind Meld!